Field of the Invention
The invention relates to aluminum-copper-magnesium alloy products, and more particularly such products, their manufacturing processes and use, designed to be used at high temperature.
Description of Related Art
Certain aluminum alloys are regularly used for applications in which they are used at high temperatures, typically between 100 and 200° C., for example as structural parts or as a means of fastening close to engines in the automobile or aerospace industry or as structural parts in supersonic aircraft.
These alloys require good mechanical performance at high temperature. Good mechanical performance at high temperature means in particular both thermal stability, i.e. that the mechanical properties measured at ambient temperature are stable after long-term aging at the application temperature, and also efficiency when hot, i.e. the mechanical properties measured at high temperature (static mechanical properties and creep strength) are high.
Among alloys known for this type of application mention may be made of alloy AA2618 which contains (as a percentage by weight):
Cu: 1.9-2.7 Mg: 1.3-1.8 Fe: 0.9-1.3. Ni: 0.9-1.2 Si: 0.10-0.25 Ti: 0.04-0.10 which was used in manufacturing Concorde.
Patent FR 2279852 by Cegedur Pechiney proposes an alloy with a low iron and nickel content composed as follows (as a percentage by weight):
Cu: 1.8-3 Mg: 1.2-2.7 Si<0.3 Fe: 0.1-0.4 Ni+Co: 0.1-0.4 (Ni+Co)/Fe: 0.9-1.3
The alloy may also contain Zr, Mn, Cr, V or Mo with contents lower than 0.4%, and possibly Cd, In, Sn or Be at less than 0.2% each, Zn at less than 8% or Ag at less than 1%. With this alloy, a substantial improvement of the stress concentration factor Klc is obtained, representing resistance to the propagation of cracks.
The subject of patent application EP 0.756.017 A1 (Pechiney Rhenalu) is an aluminum alloy with high resistance to creep composed as follows (as a percentage by weight):    Cu: 2.0-3.0 Mg: 1.5-2.1 Mn: 0.3-0.7    Fe<0.3 Ni<0.3 Ag<1.0 Zr<0.15 Ti<0.15    with Si such that: 0.3<Si+0.4Ag<0.6    other elements <0.05 each and <0.15 in total.
Patent RU2210614C1 describes an alloy composed as follows (as a percentage by weight)
Cu: 3.0-4.2 Mg: 1.0-2.2 Mn: 0.1-0.8 Zr: 0.03-0.2, Ti: 0.012-0.1. V: 0.001-0.15,
at least one element from among Ni: 0.001-0.25 and Co: 0.001-0.25, the rest aluminum. Alloy AA2219 composed as follows (as a percentage by weight) Cu: 5.8-6.8, Mn: 0.20-0.40, Ti: 0.02-0.10. Zr: 0.10-0.25 V: 0.05-0.15 Mg<0.02 is also known for high temperature applications.
These alloys have, however, inadequate mechanical properties for certain applications and also pose problems of recycling in particular because of the high percentage of iron and/or silicon and/or nickel and/or cobalt and/or vanadium.
Al—Cu—Mg Alloys are also known.
U.S. Pat. No. 3,826,688 gives information on an alloy composed as follows (as a percentage by weight), Cu: 2.9-3.7, Mg: 1.3-1.7 and Mn: 0.1-0.4.
U.S. Pat. No. 5,593,516 gives information on an alloy composed as follows (as a percentage by weight), Cu: 2.5-5.5, Mg: 0.1-2.3 within the limit of their solubility i.e. such that Cu is at the most equal to Cumax=−0.91 (Mg)+5.59.
Patent application EP 0 038 605 A1 teaches an alloy of composition (in weight %) Cu: 3.8-4.4. Mg: 1.2-1.8 et Mn: 0.3-0.9. au maximum 0.12 Si. 0.15 Fe. 0.25 Zn. 0.15 Ti et 0.10 Cr.
U.S. Pat. No. 6,444,058 teaches a composition of high purity Al—Mg—Cu alloy for which effective values for Cu and Mg are defined, especially by Cutarget═Cueff+0.74 (Mn−0.2)+2.28 (Fe−0.005) and teaches a composition domain in the diagram Cueff: Mgeff wherein the maximum value for Mgeff is about 1.4 wt. %.
There exists a need for aluminum alloy products with good mechanical performances at high temperature, typically at 150° C., and that are easy to manufacture and recycle.